Self-anchorable pipe joint

ABSTRACT

In self-anchorable pipe joints, of the kind in which a spigot at the end of one pipe is inserted into a socket at the end of the other pipe, a sealing member of tapered cross-section is placed under axial compression in the annular gap between the spigot and socket, the outer, transverse face of the sealing member is initially inclined relative to the axis of the sealing member. There is also provided an annular self-anchorable member for use in a self-anchorable pipe joint, having an anchoring face at about 60* to its axis. A pipe joint as disclosed is more resistant to leakage on angular misalignment than previous joints.

United States Patent [191 Clifford Jan. 23, 1973 [5 SELF-ANCHORABLE PIPEJOINT FOREIGN PATENTS OR APPLICATIONS [75] Inventor: Norman JohnCliliord, Beeston, 511- 730,595 3/1966 Canada ..285/32l gland 671,1039/1963 Canada ....285/321 932,001 7 1963 G tB 'ta' ..285 321 [73]Assignee: British Steel Corporation, London, I ma n m England PrimaryExaminer-David J. Williamowsky [22] Filed: 7 7 Assistant Examiner-WayneL. Shedd Attorney-Ostrolenk, Faber, Gerb & Soffen [21] Appl. No.: 64,236

[57] ABSTRACT Foreign Alllmclflon Priority in self-anchorable pipejoints, of the kind in which a a 10 1969 Great Bmain l .44 689/69 spigotat the end of one pipe is inserted into a socket at the end of the otherpipe, a sealing member of [52] U 8 Cl 285/321 285/374 taperedcross-section is placed under axial compres- 'gi' 1 21/08 sion in theannular gap between the spigot and socket, the outer, transverse face ofthe sealing member is ini- [58] Field of Search 285/321 348 tiallyinclined relative to the axis of the sealing 56 R f d member. There isalso provided an annular selfe erences I e anchorable member for use ina self-anchorable pipe UNITED STATES PATENTS joint, having an anchoringface at about 60 to its axis. A pipe joint as disclosed is moreresistant to leakage 2,877,732 3/1959 Eaton u 285/321 X on angulafmisafignment than previous jgints 2,913,264 11/1959 Suendermann........285/348X 2,722,438 11/1955 Kennison ..285/374 X 3 Claims, -2Drawing Figures v I v nu 1111111111 -r w I 3 l3 I5 u 4 z PATENTEDJAN 23I975 3,712 648 INVENTOR NQRMAN JOHN CLIFFORD SELF-ANCHORABLE PIPE JOINTThis invention relates to self-anchorable pipe joints, of the kind inwhich a spigot at the end of one pipe is inserted into a socket at theend of the other pipe and a sealing member of tapered cross-section isplaced under substantially axial compression in the annular gap betweenthe spigot and socket. it is to be understood that the spigot and/orsocket may be formed on or in an intermediate coupling member ratherthan directly on the pipes to be joined.

Previous self-anchoring pipe joints have been described for example inBritish Pat. specification Nos. 1,032,585, 1,043,063, 1,136,512,1,146,453 and 1,167,076. These joints, however, have two principaldisadvantages.

1. They must always be used as self-anchored joints having been designedand made solely for this purpose.

2. They are expensive to produce and often cumbersome to assemble.

These disadvantages were to some extent overcome by the developments ofself-anchorable pipe joints as described in British Pat. specificationNos. 932,001, 932,002 and 898,884.

All these pipe joints have been found to be satisfactory so long as thepipes remain in axial alignment, but leakage of the contents of thepipeline occurred if adjacent pipes suffered relative deflection. At lowpressures failure occurred by displacement of the rubber gasket withsubsequent leakage around the joint. At high pressures failureoccurred'by lifting of the circlip and tearing of the spigot end of thepipe. Clearly this failure placed severe limits on:

a. The pressure carrying capacity of the pipeline at any given level ofdeflection of adjacent pipe members.

b. The deflection which the pipeline will accommodate without leakage atany given level of internal pressure.

The present invention overcomes these disadvantages and therefore allowsfor much higher combinations of internal pressure and pipe deflectionthan did the previously listed joints.

In addition it may be used as a self-anchored or unanchored joint asrequired. Thus using the same joint profile a pipeline may be jointedunanchored in the most part and only anchored where necessary, i.e., to

cross a river or other such obstacle. in this case an anchoring groovemay be machined into the spigot on site.

According to one aspect of the present invention, the outer, transverseface of the sealing member, against which the substantially axialcompressing force is exerte'd, is initially'inclined relative to theaxis of the sealing member, instead of being at right angles to the axisas in previous arrangements. Alsoaccording to the invention 1 provide asealing ring for use in a selfanchorable pipe joint, having across-section comprising a first surface substantially parallel to theaxis of the ring and two further surfaces inclined at acute angles tothe first surface. The angle of inclination is preferably such that theangle included between the said face and the said axis is between 70 and80, but preferably 75.

Preferably, as in previous self-anchorable joints, an annular anchoringmember is disposed between abut- 'ments on the spigot and in the socket,to prevent axial separation of the pipes. This anchoring member isindependent of the sealing member.

secured to the socket pipe end.

One convenient embodiment of the invention is shown, by way of exampleonly, in the accompanying drawings, in which:

FIG. 1 shows the components of a self-anchorable joint before assembly,and

FIG. 2 shows the joint after assembly.

The drawings show a pipe end 1 formed with an enlarged portioncontaining a socket 2, and a pipe end 3 forming a-spigot 4 with achamfered tip 5. The pipe end 1 had a flange 6 receiving a plurality ofbolts 7 (only one being shown). A gland ring 8 which encircles the pipeend 3 is secured to the bolts 7 by nuts 9.

The socket has an internal groove 10 and the spigot has a correspondingexternal groove 11. An anchoring ring 12, in the nature of a split ringor circlip is sprung into the groove 10 and the spigot is pushed intothe socket until the groove 11 registers with the groove 10 and the ring12 springs into the groove 11, thereby axially securing and locating thepipeends. The grooves have flat base surfaces and the groove 10 has atapered surface, the ring 12 having a wedge shaped side whose twotapered surfaces co-operate with the tapered surface of the groove 10and the chamfered tip of the spigot to force the ring into the groove 11when the pipes are subjected to a force tending to separate them, and tofacilitate insertion of the spigot, respectively.

The angle of the tapered surface of the groove 10 lies within the rangeto 70 to the socket pipe axis, but preferably at lnthe undeflectedposition, the angle between the tapered surface of the groove 10 and theAccording to another aspect of the present invention, the included angleat the nose of the sealing member i.e., the angle of taper of the crosssection of the sealing member, is made larger than hitherto, beingpreferably about 30.

co-operating tapered surface of the ring 12 is substantially 5 to allowa 3 deflection of the joint from the socket face. I

It has been established that with the tapered surface of groove 10 at anangle of 65, a satisfactory downward component of thrust will bedirected onto the ring 12 thus ensuring firm engagement of ring 12 inspigot groove ll.- investigations have shown thatring 12 resulting intwisting of the ring 12 and possible displacement from the spigot groove11.

Further investigations have shown that without the 5 difference in theangles between the co-operating tapered surfaces of the groove 10 andthe ring 12 any small deflection of the spigot 4 in the socket 1 willcause contact of the extreme outer edge of the tapered surface of thering 12 with groove 10. Contact at this point will induce a high turningmoment into the ring 12 impairing its stability in the spigot groove 11and will also restrict movement of the tapered surface of ring 12 alongthe co-operating surface of groove 10. It has been found that the 5angle increases the resistance of ring 12 to rotation in spigot groove11 since this causes the thrust to be applied at the nearest point onthe tapered surface of ring 12 to the groove 11 making the turningmoment on ring 12 a minimum and ensures that this condition ismaintained throughout the full working deflection of the joint. Inaddition this difference in angle facilitates movement of ring 12 alongthe tapered surface of the groove as the joint is deflected and allowsthe spigot 4 to remain centralized within the gasket ring 13.

Sealing of the joint is effected by a gasket ring 13 made of resilientmaterial e.g., rubber and preferably provided with soft metalreinforcement. The ring 13 has a triangular cross-section with one faceparallel to the axis of the ring and of the pipes, and a second face atan angle of between 25 and 35, but preferably 30 to the first face.These two faces engage respectively the outer surface of the spigot andthe inner surface of a correspondingly tapered portion 14 of the socket.In the assembled joint, the nuts 9 are screwed up so that the gland 8presses against the third outer face of the ring 13, thereby axiallycompressing the ring. Owing to the resilience of the material of thering, it is compressed against the adjacent surfaces of the spigot andsocket. Hitherto, the outer face of the ring has been made initially atright angles to the axis of the ring. In contrast, in the present joint,this face is initially between 70 and 80, preferably 75, to the axis,that is, between 10 and 20, preferably 15, to a plane at right angles tothe axis.

Tests show that as the angle is reduced to below 15 the effective spaceinto which the rubber can flow when compressed is also reduced. Thisimpairs the sealing efficiency of the joint since the rubber is lessable to conform to the spigot surface when the joint deflects. As theangle increases above l5 there is an increasing risk of rubber becomingtrapped between the spigot and the gland nose with a resultant loss ofgasket compression.

The joint described has been found to provide reliable sealing even whenthe pipes are deflected relative to one another.

Our investigations have shown that in the previous joints with the outerface of the sealing ring at right angles to the axis, deflection of thepipes caused the joint to pivot around the anchoring ring, therebyeffectively reducing the compression of the sealing ring and permittingleakage. It was found that the previous design of sealing ring wasinitially heavily compressed against the internal surface of the socket,but not sufficiently strongly compressed against the external surface ofthe spigot. We have found that by making the outer surface of the ringoblique the effective compression against the outer surface of thespigot can be substantially increased, thereby preventing leakage whenthe pipes are deflected. A large angle of taper of the sealing ring,

e.g., 30 as shown, also improves the sealing, and the gasket is largerthan those used hitherto. Investigations have shown that as the taperedsurface of the sealing ring diverges from 30, there is progressivereduction in sealing efficiency when the joint is deflected. In the caseof angles below 30, gasket compression reduces rapidly with deflectiondue to the progressive loss in volume of rubber available to accommodatespigot movement. As the angle exceeds 30, the wedging action of thegasket becomes progressively impaired and sealing efficiency on theprotective nose of the gasket is thus reduced. It is to be understoodthat, in the assembled joint, the outer face of the sealing ring will bedeformed and will not remain at an angle of to the axis. Suchdeformation is shown in FIG. 2.

It will be seen that the throat of the socket is stepped so as toprovide a large tapered chamber to receive the sealing ring with itsnose projecting into the gap between the spigot and the socket, and anarrow throat at 15 adjacent to the anchoring ring.

I claim:

1. In a spigot and socketjoint comprising,

a spigot having a longitudinal axis of extension, and

including a circumferential exterior surface extending generally alongsaid axis; said spigot including an inlet which is inserted into asocket; socket having an axis of extension substantially parallel tosaid spigot axis; said socket having an inlet; said socket including anopening extending back from said inlet, which said opening is defined bythe surrounding socket wall; said socket wall being spaced away fromsaid spigot surface and surrounding said spigot inlet and surface todefine an annular gap therebetween; said surrounding socket wallincluding a tapered portion which tapers inwardly toward said spigotinlet, thereby tapering said annular gap;

a resilient sealing member interposed in said annular gap and includinga surface which engages said socket wall tapered portion and engagesthat portion of said spigot exterior surface opposed to said socket walltapered portion; said resilient member having a tapered shape to conformto the aforesaid tapered shape of said annular gap; said resilientmember having a transverse surface facing away from said spigot inlet;

a compressive member carried by and attached to said joint and having apressure face positioned such that it is moved into engagement with saidresilient member transverse surface to axially compress said resilientmember;

the improvement comprising,

when said pressure face of said compressive member is moved intoengagement with said resilient member transverse surface, said pressureface is oriented and positioned so as to be at a predetermined inclinewith respect to said resilient member transverse surface and so as tobear initially upon that radially inmost portion of said transversesurface that is closest to said spigot exterior surface,

anchoring means communicating with both of said spigot and said socketto secure them together and prevent axial separation thereof,

each of said spigot and said socket having an abutment extending intosaid annular gap; said anchorsuch that the angle formed between thesesaid surfaces is approximately 5.

2. In a spigot and socket joint comprising,

a spigot, including a circumferential exterior surface that is insertedinto a socket;

a sockethaving an axis of extension, said socket ineluding an inlet andincluding an opening extending back from said inlet, that is defined bya surrounding socket wall; said spigot being inserted into said socketopening;

said socket surrounding wall including an annular groove; said spigotcircumferential surface including a annular groove, said annular groovesbeing so positioned relative to each other as to receive an annularanchoring member which is sprung into both said grooves, thereby toprevent axial separation of said socket and said spigot;

the improvement comprising,

said socket groove being defined on the side thereof facing toward saidsocket inlet by a side wall which is inclined at an angle to said socketaxis of 60 and said anchoring member including an abutting surface whichabuts said socket groove inclined side wall and which anchoring memberabutting surface is inclined at an angle to the socket axis ofapproximately 5 less than the angle of incline of said socket grooveside wall.

3. In a spigot and socket joint comprising,

a spigot, including a circumferential exterior surface that is insertedinto a socket;

a socket having an axis of extension, said socket including an inlet andincluding an opening extending back from said inlet, that is defined bya surrounding socket wall; said spigot being inserted into said socketopening;

said socket surrounding wall including an annular groove; said spigotcircumferential surface including an annular groove, said annulargrooves being so positioned relative to each other as to receive anannular anchoring member which is sprung into both said grooves, therebyto prevent axial separation of said socket and said spigot;

the improvement comprising,

said socket groove being defined on the side thereof facing toward saidsocket inlet by a side wall which is inclined at an angle to said socketaxis of 60 to 70;

said anchoring member including an abutting surface which abuts saidsocket groove inclined side wall 'said abutting surface of saidanchoring member being inclined to the socket axis and forming a sharplyacute angle with the socket groove side wall.

1. In a spigot and socket joint comprising, a spigot having alongitudinal axis of extension, and including a circumferential exteriorsurface extending generally along said axis; said spigot including aninlet which is inserted into a socket; a socket having an axis ofextension substantially parallel to said spigot axis; said socket havingan inlet; said socket including an opening extending back from saidinlet, which said opening is defined by the surrounding socket wall;said socket wall being spaced away from said spigot surface andsurrounding said spigot inlet and surface to define an annular gaptherebetween; said surrounding socket wall including a tapered portionwhich tapers inwardly toward said spigot inlet, thereby tapering saidannular gap; a resilient sealing member interposed in said annular gapand including a surface which engages said socket wall tapered portionand engages that portion of said spigot exterior surface opposed to saidsocket wall tapered portion; said resilient member having a taperedshape to conform to the aforesaid tapered shape of said annular gap;said resilient member having a transverse surface facing away from saidspigot inlet; a compressive member carried by and attached to said jointand having a pressure face positioned such that it is moved intoengagement with said resilient member transverse surface to axiallycompress said resilient member; the improvement comprising, when saidpressure face of said compressive member is moved into engagement withsaid resilient member transverse surface, said pressure face is orientedand positioned so as to be at a predetermined incline with respect tosaid resilient member transverse surface and so as to bear initiallyupon that radially inmost portion of said transverse surface that isclosest to said spigot exterior surface, anchoring means communicatingwith both of said spigot and said socket to secure them together andprevent axial separation thereof, each of said spigot and said sockethaving an abutment extending into said annular gap; said anchoring meanscomprising an annular self-anchoring member which engages said abutmentsand thereby prevents axial separation, said socket abutments comprise asurface inclined at an angle of 60* - 70* to said socket axis andinclined, measuring into said annular gap, toward said socket inlet,said anchoring member including an abutting surface that abuts againstsaid socket abutment surface; said anchoring member being shaped suchthat its said abutting surface is inclined at an angle with respect tosaid socket axis that is less than the angle of incline of said socketabutment surface, such that the angle formed between these said surfacesis approximately 5*.
 2. In a spigot and socket joint comprising, aspigot, including a circumferential exterior surface that is insertedinto a socket; a socket having an axis of extension, said socketincluding an inlet and including an opening extending back from saidinlet, that is defined by a surrounding socket wall; said spigot beinginserted into said socket opening; said socket surrounding wallincluding an annular groove; Said spigot circumferential surfaceincluding a annular groove, said annular grooves being so positionedrelative to each other as to receive an annular anchoring member whichis sprung into both said grooves, thereby to prevent axial separation ofsaid socket and said spigot; the improvement comprising, said socketgroove being defined on the side thereof facing toward said socket inletby a side wall which is inclined at an angle to said socket axis of 60*and 70*; said anchoring member including an abutting surface which abutssaid socket groove inclined side wall and which anchoring memberabutting surface is inclined at an angle to the socket axis ofapproximately 5* less than the angle of incline of said socket grooveside wall.
 3. In a spigot and socket joint comprising, a spigot,including a circumferential exterior surface that is inserted into asocket; a socket having an axis of extension, said socket including aninlet and including an opening extending back from said inlet, that isdefined by a surrounding socket wall; said spigot being inserted intosaid socket opening; said socket surrounding wall including an annulargroove; said spigot circumferential surface including an annular groove,said annular grooves being so positioned relative to each other as toreceive an annular anchoring member which is sprung into both saidgrooves, thereby to prevent axial separation of said socket and saidspigot; the improvement comprising, said socket groove being defined onthe side thereof facing toward said socket inlet by a side wall which isinclined at an angle to said socket axis of 60* to 70*; said anchoringmember including an abutting surface which abuts said socket grooveinclined side wall said abutting surface of said anchoring member beinginclined to the socket axis and forming a sharply acute angle with thesocket groove side wall.